Tire curing systems are known to generally present one or more molds, each comprising a top and bottom mold half, defining an annular chamber for a green tire. The top mold half is usually connected to a moving crosspiece on the press, whereas the bottom mold half is mounted on the bed of the press and supports a deformable inner tube or curing bladder designed to occupy the said annular chamber when inflated with a heat-exchanging medium or media such as gas. The said gas, usually consisting of relatively hot steam, is supplied under pressure by an external feeder, which provides for heating the gas and circulating it under pressure inside the mold for the length of time required for curing.
A major drawback of known systems of the aforementioned type is that they involve relatively high manufacturing cost and provide for relatively low output. Such systems, in fact, require a relatively high-cost press for every one or two molds, which press remains engaged throughout the entire curing operation.
To overcome this drawback, systems have been devised comprising a number of molds mounted in a fixed manner on an indexing fixture which, turning about a fixed vertical axis, feeds the molds, one by one, through a loading station where each mold is opened, loaded and closed by a fastening device on the mold itself. The mold is then turned on the indexing fixture and supplied, as long as required for curing, with heat-exchanging gas fed under pressure from a centralized feeding device connected to all the molds on the indexing fixture.
Though systems of the aforementioned type involve no presses and provide for using a large number of molds at the same time, they are nevertheless extremely expensive in that they require a separate system for heating and supplying gas under pressure, as well as a number of sliding joints for connecting each moving mold to the said system.
Furthermore, the said indexing fixture, to which the bottom part of each mold is connected integrally, imposes the same curing time for each mold, with no possibility of selective curing.